There are a number of processes for reducing the alcohol content in fermented drinks such as wine, beer and champagne. In one such process, as disclosed in European published specification No. 0 058 634, the fermented drink is subjected to a fractional distillation operation in order to remove therefrom the alcohol (ethanol). In order not to subject the drink to an excessively high level of temperature loading, in order to avoid the taste thereof being affected, the distillation operation may be carried out under vacuum. That process also provides that the taste and aroma substances which are removed in the fractional distillation operation, besides the ethanol, are added back to the drink to put it into its finished form. In spite of using fractional vacuum distillation and evaporators which permit evaporation to be as quick and as careful as possible, for example thin-film evaporators, that process provides that the finished product suffers from the disadvantage that the taste thereof is adversely affected and there are serious deviations from the true taste of the original drink.
In another process, the ethanol in a fermented drink may also be extracted by means of organic solvents. Apart from the fact that the use of such a process is in conflict with the provisions of foodstuffs laws, that process also results in the taste of the drink being adversely affected.
In a number of other forms of a process for reducing the alcohol content in a fermented drink, the alcohol content may be reduced by carrying out a dialysis operation in which the fermented drink, for example wine, flows on one side of a dialysis membrane while a dialysing liquid, for example water, flows on the other side of the membrane, preferably in counter-flow relationship to the fermented drink. The differential pressure between the two liquids is very slight or even zero. The critical consideration in regard to the interchange of substances in the dialysis operation is diffusion through the membrane, which depends on the ratio between the levels of concentration of the respective substances on the two sides of the membrane. In that respect attention may be directed to European patent specification No. 0 021 247 and also German laid-open application (DE-OS) No. 30 09 829. In one form of such a process, the dialysis liquid used may be an alcohol-free drink, for example a fruit juice, or a drink corresponding to the drink to be dialysed, and the dialysed alcohol may be removed by vacuum distillation.
However, those processes are such that the taste of the finished product is still adversely affected by the steps involved in the process.